CN108897085B - Optical filter and infrared image sensing system comprising same - Google Patents

Abstract

The invention relates to a light filter and an infrared image sensing system comprising the light filter, wherein the light filter comprises a glass substrate, and an IR film layer and an AR film layer which are plated on two opposite surfaces of the glass substrate, wherein the IR film layer comprises a first refractive index material layer, a second refractive index material layer and a third refractive index material layer; the refractive index of the third refractive index material layer is larger than that of the first refractive index material layer, and the refractive index of the second refractive index material layer is larger than that of the third refractive index material layer. The optical filter has good anti-reflection effect on near infrared light, thereby ensuring higher precision on face recognition and gesture recognition. In addition, the film thickness of the optical filter provided by the invention is thinner, and meanwhile, the adhesive force of the optical filter film can be effectively improved.

Description

Filter and infrared image sensing system including the filter

Technical Field

The present invention belongs to the field of optical sensing technology, and in particular relates to a filter and an infrared image sensing system including the filter.

Background technique

With the development of technology, facial recognition, gesture recognition and other functions have been gradually embedded in terminals such as smartphones, vehicle-mounted laser radar, security access control, smart homes, virtual reality/augmented reality/mixed reality, 3D somatosensory games, 3D cameras and displays.

Near-infrared narrow-band filters are required for face recognition and gesture recognition, which can play the role of enhancing the transmittance of near-infrared light in the passband and cutting off visible light in the environment. Usually, near-infrared narrow-band filters include two film systems, namely IR bandpass film system and long-wave pass AR film system. However, the filter in the prior art has poor transmittance enhancement effect on near-infrared light and poor visible light cutting effect. At the same time, there are problems such as thick film layer thickness and poor film layer adhesion, which leads to poor imaging effect and low recognition accuracy after the filter is assembled into face recognition, gesture recognition and other devices.

Summary of the invention

The object of the present invention is to provide a filter and an infrared image sensing system comprising the filter, so as to solve the problems of poor near-infrared light transmittance enhancement effect and poor film adhesion of the existing filter.

To achieve the above object, the present invention provides a filter, comprising a glass substrate and an IR film layer and an AR film layer coated on two opposite surfaces of the glass substrate.

The IR film layer comprises a first refractive index material layer, a second refractive index material layer and a third refractive index material layer;

The refractive index of the third refractive index material layer is greater than the refractive index of the first refractive index material layer, and the refractive index of the second refractive index material layer is greater than the refractive index of the third refractive index material layer.

According to one aspect of the present invention, the AR film layer includes a first refractive index material layer and a second refractive index material layer or includes a first refractive index material layer, a second refractive index material layer and a third refractive index material layer.

According to one aspect of the present invention, in a direction away from the glass substrate, the outermost layer of the IR film layer and the outermost layer of the AR film layer are layers of a first refractive index material.

According to one aspect of the present invention, along the direction away from the glass substrate, the structure of the IR film layer is M, (LH)*n, L in sequence, wherein M represents the third refractive index material layer, L represents the first refractive index material layer, H represents the second refractive index material layer, (LH)*n represents that the first refractive index material layer and the second refractive index material layer are alternately arranged n times, and n is an integer greater than or equal to 1.

According to one aspect of the present invention, along the direction away from the glass substrate, the structure of the IR film layer is (LH)*s, L, M, (LH)*p, L in sequence, wherein M represents the third refractive index material layer, L represents the first refractive index material layer, H represents the second refractive index material layer, (LH)*s represents that the first refractive index material layer and the second refractive index material layer are alternately arranged s times, s is an integer greater than or equal to 0, (LH)*p represents that the first refractive index material layer and the second refractive index material layer are alternately arranged p times, p is an integer greater than or equal to 1.

According to one aspect of the present invention, along the direction away from the glass substrate, the structure of the AR film layer is (LH)*q, L in sequence, wherein L represents the first refractive index material layer, H represents the second refractive index material layer, and (LH)*q represents that the first refractive index material layer and the second refractive index material layer are alternately arranged q times, and q is an integer greater than or equal to 1.

According to one aspect of the present invention, along the direction away from the glass substrate, the structure of the AR film layer is M, (LH)*k, L in sequence, wherein M represents the third refractive index material layer, L represents the first refractive index material layer, H represents the second refractive index material layer, (LH)*k represents that the first refractive index material layer and the second refractive index material layer are alternately arranged k times, and k is an integer greater than or equal to 1.

According to one aspect of the present invention, along the direction away from the glass substrate, the structure of the AR film layer is (LH)*i, L, M, (LH)*f, L in sequence, wherein M represents the third refractive index material layer, L represents the first refractive index material layer, H represents the second refractive index material layer, (LH)*i represents that the first refractive index material layer and the second refractive index material layer are alternately arranged i times, i is an integer greater than or equal to 0, (LH)*f represents that the first refractive index material layer and the second refractive index material layer are alternately arranged f times, f is an integer greater than or equal to 1.

According to one aspect of the present invention, the physical thickness of the second refractive index material layer and the physical thickness of the first refractive index material layer satisfy the relationship: 0.05≤D _L /D _H ≤20, and the physical thickness of the third refractive index material layer and the physical thickness of the second refractive index material layer satisfy the relationship: 0.02≤D _M /D _H ≤50.

According to one aspect of the present invention, the second refractive index material layer of the IR film layer is a hydrogenated silicon layer, the refractive index in the wavelength range of 800-1200nm is greater than 3.5, and the extinction coefficient is less than 0.002;

The refractive index of the second refractive index material layer is greater than 3.6 at 850 nm and greater than 3.55 at 940 nm.

According to one aspect of the present invention, the silicon hydrogenation layer is a sputtering reaction coating material layer, the sputtering temperature range is 80-300 degrees Celsius, the hydrogen flow rate is 10-50sccm, and the sputtering rate is 0.1nm/s-1nm/s.

According to one aspect of the present invention, within the wavelength range of 800-1200nm, the refractive index of the medium refractive index material layer is less than 4, and the refractive index of the low refractive index material layer is less than 3.

According to one aspect of the present invention, the IR film layer has a passband, two cutoff bands and two transition bands in the wavelength range of 800-1200nm, the two transition bands are respectively located on both sides of the passband, and the two cutoff bands are respectively outside the two transition bands;

The passband width is less than 400nm and the transmittance is greater than 90%;

The transmittance of the transition band is 0.1%-90%;

The transmittance of the cut-off band is less than 0.1%.

According to one aspect of the present invention, the AR film layer has a passband, a cutoff band and a transition band in the wavelength range of 350-1200nm, and along the direction from 350nm to 1200nm, the cutoff band, the transition band and the passband band are arranged in sequence;

The transmittance of the passband is greater than 90%;

The transmittance of the transition band is 0.1%-90%;

The transmittance of the cut-off band is less than 0.1%.

According to one aspect of the present invention, the full width at half maximum of the filter is less than 120 nm, and the total thickness of the IR film layer and the AR film layer is less than 9.8 microns.

According to one aspect of the present invention, when the incident angle changes from 0° to 30°, the center wavelength shift of the filter passband is less than 20nm.

To achieve the above object, the present invention provides an external infrared image sensing system including the above filter, comprising a light source unit and a receiving unit.

The light source unit includes an IR emitting light source and a first lens assembly;

The receiving unit includes a second lens assembly, a filter and an infrared image sensor.

According to one solution of the present invention, the IR film layer and the AR film layer are arranged in the above manner, and while effectively ensuring the high transmittance of near-infrared light, the drift of the center wavelength of the filter passband with angle can be controlled to be less than 20nm. In addition, since the third refractive index material layer M is provided in the IR film layer and the AR film layer, and arranged in the above arrangement form, the total film thickness of the filter of the present invention is effectively reduced, and the adhesion of the film layer can be improved.

According to one embodiment of the present invention, the present invention provides an infrared image sensing system including the optical filter of the present invention. Since the optical filter of the present invention is provided, the near-infrared light can be transmitted and the light of other bands can be cut off during shooting, thereby improving the accuracy of final face recognition and gesture recognition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a diagram schematically showing the structure of an IR film layer according to an embodiment of the present invention;

FIG2 is a diagram schematically showing the structure of an AR film layer according to an embodiment of the present invention;

FIG3 is a diagram schematically showing the light wavelength transmittance curve of the IR film layer in Example 1;

FIG4 is a diagram schematically showing a light wavelength transmittance curve of the AR film layer in Example 1;

FIG5 is a diagram schematically showing the light wavelength transmittance curve of the IR film layer in Example 2;

FIG6 is a diagram schematically showing the light wavelength transmittance curve of the AR film layer in Example 2;

FIG7 is a diagram schematically showing the light wavelength transmittance curve of the IR film layer in Example 3;

FIG8 is a diagram schematically showing the light wavelength transmittance curve of the AR film layer in Example 3;

FIG. 9 is a diagram schematically showing the structure of an infrared image sensing system including the filter of the present invention.

The meanings of the symbols in the accompanying drawings are as follows:

1. Glass substrate. 2. IR film layer. 3. AR film layer. L. Low refractive index material layer. M. Medium refractive index material layer. H. High refractive index material layer. 4. Light source unit. 41. IR light source. 42. First lens assembly. 5. Receiving unit. 51. Second lens barrel assembly. 52. Filter. 53. Infrared image sensor. 6. Face/hand.

Detailed ways

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative work.

When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

FIG. 1 is a schematic diagram showing the structure of an IR film layer according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of an AR film layer according to an embodiment of the present invention. As shown in FIG. 1 and FIG. 2, the optical filter of the present invention comprises a glass substrate 1, an IR film layer 2 and an AR film layer 3. The glass substrate 1 of the present invention can be D263T or AF32, the IR film layer 2 is an infrared cut-off film layer, and the AR film layer 3 is an anti-reflection film, i.e., an anti-reflection film, which can have an anti-reflection effect on wavelengths within a specific range. The IR film layer 2 and the AR film layer 3 are respectively coated on two opposite surfaces of the glass substrate 1. In this embodiment, the IR film layer 2 is coated on the upper surface of the glass substrate 1, and the AR film layer 3 is coated on the lower surface of the glass substrate 1.

As shown in FIG1 , in this embodiment, the IR film layer 2 of the optical filter of the present invention includes a first refractive index material layer L, a third refractive index material layer M, and a second refractive index material layer H. In this embodiment, the IR film layer 2 includes four material layers in total, which are the third refractive index material layer M, the first refractive index material layer L, the second refractive index material layer H, and the first refractive index material layer L along the direction away from the glass substrate 1. This structure can be expressed as M, (LH), L, that is, in this embodiment, the IR film layer 2 includes a three-layer structure, which are the third refractive index material layer M coated on the upper surface of the glass substrate 1, the outermost first refractive index material layer L, and the intermediate material layer between the third refractive index material layer M and the outermost first refractive index material layer L. In this embodiment, the intermediate material layer includes the first refractive index material layer L and the second refractive index material layer H in sequence. The intermediate material layer of the IR film layer 2 of the present invention may include a plurality of first refractive index material layers L and second refractive index material layers H alternately arranged, that is, the structure of the IR film layer 2 of the present invention can be expressed as M, (LH)*n, L, that is, along the direction away from the glass substrate 1, the IR film layer 2 sequentially includes a third refractive index material layer M, an intermediate material layer and a first refractive index material layer L, and the intermediate material layer is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged n times, and n is an integer greater than or equal to 1.

In addition, the IR film layer 2 of the present invention may have other embodiments in addition to the structural form of the above-mentioned embodiment. In the second embodiment of the IR film layer 2 of the present invention, the structure of the IR film layer 2 is (LH)*s, L, M, (LH)*p, L, that is, along the direction away from the glass substrate 1, the IR film layer 2 includes a total of five layers, the first layer structure is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged s times, s is an integer greater than or equal to 0. The second layer structure is the first refractive index material layer L, the third layer is the third refractive index material layer M, the fourth layer structure is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged p times, p is an integer greater than or equal to 1, and the fifth layer structure, i.e., the outermost layer, is the first refractive index material layer L.

The IR film layer 2 of the present invention includes a third refractive index material layer M, a first refractive index material layer L and a second refractive index material layer H, and is arranged according to the above embodiment, which can effectively improve the adhesion of the film layer and improve the near-infrared light transmittance curve characteristics.

As shown in FIG2 , the AR film layer 3 of the present invention is plated on the lower surface of the glass substrate 1. In the present embodiment, the AR film layer 3 includes a low refractive index material layer L and a high refractive index material layer H. Specifically, along the direction away from the glass substrate 1, the AR film layer 3 includes a first refractive index material layer L, a second refractive index material layer H and a first refractive index material layer L in sequence. In the present embodiment, the structure of the AR film layer 3 can be expressed as (LH), L, that is, along the direction away from the glass substrate 1, the AR film layer 3 includes a total of two layers of structure, which are a first structural layer formed by alternately plating the first refractive index material layer L and the second refractive index material layer H and the outermost first refractive index material layer L. In addition, the first refractive index material layer L and the second refractive index material layer H in the first structural layer of the AR film layer 3 of the present invention can also be alternated multiple times, that is, the structure of the AR film layer 3 can be expressed as (LH)*q, L, (LH)*q means that the first refractive index material layer L and the second refractive index material layer H are alternately arranged q times, and q can be an integer greater than or equal to 1.

According to a second embodiment of the AR film layer 3 of the present invention, the structure of the AR film layer 3 is M, (LH)*k, L, that is, along the direction away from the glass substrate 1, the AR film layer 3 sequentially includes a third refractive index material layer M, an intermediate material layer and a first refractive index material layer L, and the intermediate material layer is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged k times, and k is an integer greater than or equal to 1.

In addition, when the AR film layer 3 of the present invention includes a first refractive index material, a second refractive index material and a third refractive index material layer, the structure of the AR film layer 3 can also be (LH)*i, L, M, (LH)*f, L, that is, along the direction away from the glass substrate 1, the AR film layer 3 includes a total of five layers, the first layer structure is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged i times, i is an integer greater than or equal to 0. The second layer structure is the first refractive index material layer L, the third layer is the third refractive index material layer M, the fourth layer structure is composed of the first refractive index material layer L and the second refractive index material layer H alternately arranged f times, f is an integer greater than or equal to 1, and the fifth layer structure, i.e., the outermost layer, is the first refractive index material layer L.

The IR film layer 2 and the AR film layer 3 included in the optical filter of the present invention can be selected from any one of the above-mentioned embodiments, that is, the IR film layer 2 of the present invention has two embodiments, and the AR film layer 3 has three embodiments. When manufacturing the optical filter of the present invention, the embodiments of the IR film layer 2 and the AR film layer 3 can be freely combined. It should be noted that no matter which embodiment is adopted, the outermost layer of the IR film layer 2 and the outermost layer of the AR film layer 3 are both low refractive index material layers.

In the optical filter of the present invention, the high refractive index material layer H involved in the IR film layer 2 is a hydrogenated silicon layer. The hydrogenated silicon layer is plated by sputtering reaction during plating. During plating, the temperature is controlled within the range of 80°C-300°C, the hydrogen flow rate is controlled to be 10-50sccm, and the sputtering speed is controlled to be 0.1nm/s-1nm/s, so that the refractive index of the second refractive index material layer H of the present invention in the range of 800-1200nm is greater than 3, the extinction coefficient is less than 0.002, the refractive index at 850nm is greater than 3.6, and the refractive index at 960nm is greater than 3.55, which is conducive to adjusting the offset of the passband center wavelength of the optical filter of the present invention. The second refractive index material layer H involved in the AR film layer 3 of the present invention can be selected from hydrogenated silicon material layer, and can also be realized by other materials, that is, the refractive index of the second refractive index material layer is greater than the refractive index of the third refractive index material layer and the first refractive index material layer.

The material used for the third refractive index material layer M involved in the IR film layer 2 and the AR film layer 3 can be selected from one or more of Sb ₂ S ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , Pr ₆ O ₁₁ , La ₂ O ₃ , Si ₂ N, SiN, Si ₂ N ₃ , and Si ₃ N ₄ ; the material used for the first refractive index material layer L involved in the IR film layer 2 and the AR film layer 3 can be selected from one or more of SiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , Pr ₆ O ₁₁ , La ₂ O ₃ , Si ₂ N, SiN, Si ₂ N ₃ , and Si ₃ N ₄ . In the wavelength range of 800-1200nm, the refractive index range of the third refractive index material layer M is less than 4, and the refractive index range of the first refractive index material layer L is less than 3. It is necessary to ensure that the refractive index of the third refractive index material layer M is greater than the refractive index of the first refractive index material layer L, that is, when the first refractive index material layer L uses one of the above materials, the material selection of the third refractive index material layer M should satisfy that the refractive index of the material selected for the third refractive index material layer is greater than the refractive index of the material selected for the first refractive index material layer L. The third refractive index material layer M and the first refractive index material layer L can be plated using a sputtering reaction device or a vacuum evaporation device.

The optical filter of the present invention is described in detail below through specific embodiments.

Embodiment 1:

In this embodiment, along the direction away from the glass substrate 1, the structure of the IR film layer 2 of the filter is M, (LH)*n, L, wherein the optical thicknesses of the second refractive index material layer H, the third refractive index material layer M and the first refractive index material layer L are respectively one-fourth of the reference wavelength, the physical thickness of the second refractive index material layer H and the physical thickness of the first refractive index material layer L satisfy the relationship: 0.05≤D _L /D _H ≤20, and the physical thickness of the third refractive index material layer M and the physical thickness of the second refractive index material H layer satisfy the relationship: 0.02≤D _M /D _H ≤50. n=11, and the total thickness of the IR film layer 2 is 3.41 μm. Along the direction away from the glass substrate 1, the structure of the AR film layer 3 is (LH)*q, L, q=12. The physical thickness of the second refractive index material layer H and the physical thickness of the low refractive index material layer L satisfy the relationship: 0.05≤D _L /D _H ≤20, and the physical thickness of the third refractive index material layer M and the physical thickness of the second refractive index material layer H satisfy the relationship: 0.02≤D _M /D _H ≤50.

That is, in this embodiment, the IR film layer 2 includes 24 material layers, and the AR film layer 3 includes 25 material layers. In this embodiment, hydrogenated silicon material layer is selected as the second refractive index material layer H, aluminum oxide is selected as the third refractive index material layer M, and silicon dioxide is selected as the first refractive index material layer L. Using the formula OT _i =OT(1+Acos(2×pi×f×i)sin(2×pi×f×i)), substitute into the equation The film parameters are as follows:

Wherein, OT _i represents the optical thickness of the i-th film layer, OT ₀ represents the optical thickness of one quarter of the design wavelength, pi represents the circumference, and f represents the modulation factor, which is between 0 and 1.

Table 1 shows the parameters of each material layer of the IR film layer 2:

Table 1

Table 2 shows the parameters of each material layer of the AR film layer 3:

1 2 3 4 5 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 118.99 144.41 121.91 40.98 99.76 6 7 8 9 10 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 38.13 108.77 46.76 96.72 40 11 12 13 14 15 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) twenty one 105 114.2 162.36 134.9 16 17 18 19 20 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 20 20 20 86.73 41.24 twenty one twenty two twenty three twenty four 25 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 117.94 60.05 45.65 53.89 139.6

Table 2

As shown in Fig. 3, the optical filter of the present invention is set with reference to the parameters of each condition in Example 1. In the wavelength range of 800-1200nm, the IR film layer 2 of the present invention has a passband, two cut-off bands and two transition bands, that is, along the direction from 800nm-1200nm, the IR film layer 2 has a cut-off band, a transition band, a passband, a transition band and a cut-off band in sequence. The passband band refers to the band through which light can pass, the cut-off band refers to the band through which light cannot pass, and the transition band is located between the cut-off band and the passband band. As shown in the figure, the width of the passband band is less than 400nm, the transmittance is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cut-off band is less than 0.1%.

As shown in Fig. 4, the AR film layer 3 of the optical filter of the present invention is set with reference to the various condition parameters in the embodiment. In the wavelength range of 350-1200nm, the AR film layer 3 has a passband, a cutoff band and a transition band, that is, along the direction from 350nm to 1200nm, the AR film layer 3 has a cutoff band, a transition band and a passband in sequence. As shown in Fig. 4, the light transmittance of the passband is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cutoff band is less than 0.1%.

The optical filter of the present invention is set according to the parameters of Example 1, which can ensure that the half-maximum full width of the optical filter of the present invention is less than 120nm, the total thickness of the IR film layer 2 and the AR film layer is less than 9.8 microns, and when the incident angle changes from 0° to 30°, the center wavelength offset of the filter passband is less than 20nm.

Embodiment 2:

In this embodiment, along the direction away from the glass substrate 1, the structure of the IR film layer 2 of the filter is (LH)*s, L, M, (LH)*p, L, wherein the optical thicknesses of the second refractive index material layer H, the third refractive index material layer M and the first refractive index material layer L are respectively one-fourth of the reference wavelength, the physical thickness of the second refractive index material layer H and the physical thickness of the first refractive index material layer L satisfy the relationship: 0.05≤D _L /D _H ≤20, and the physical thickness of the third refractive index material layer M and the physical thickness of the second refractive index material layer H satisfy the relationship: 0.02≤D _M /D _H ≤50. s＝5, p＝6, and the total thickness of the IR film layer 2 is 3.2μm. Along the direction away from the glass substrate 1, the structure of the AR film layer 3 is (LH)*q, L, q＝12. The physical thickness of the second refractive index material layer H satisfies the relationship of 0.05≤D _L /D _H ≤20 with the physical thickness of the first refractive index material layer L, and the physical thickness of the third refractive index material layer M satisfies the relationship of 0.02≤D _M /D _H ≤50 with the physical thickness of the second refractive index material layer H.

That is, in this embodiment, the IR film layer 2 includes 25 material layers, and the AR film layer 3 includes 25 material layers. In this embodiment, hydrogenated silicon material is selected as the second refractive index material layer H in the IR film layer 2, aluminum oxide is selected as the third refractive index material layer M, and silicon dioxide is selected as the first refractive index material layer L. In the AR film layer 3, Nb ₂ O ₅ is selected as the second refractive index material layer, and silicon dioxide is selected as the first refractive index material layer L. Using the formula OT _i =OT(1+Acos(2×pi×f× i)sin(2×pi×f×i)), substitute into the equation The film parameters are as follows:

Table 3 shows the parameters of each material layer of the IR film layer 2:

1 2 3 4 5 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 216.82 241.04 157.35 258.55 110.97 6 7 8 9 10 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 72.68 110.1 281.69 31.92 105.95 11 12 13 14 15 Material SiO _{2 AL2O3 ​} SiO ₂ Si:H SiO ₂ Thickness(nm) 115.24 269.55 20 229.1 85.05 16 17 18 19 20 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 244.25 20 163.62 80.54 70.93 twenty one twenty two twenty three twenty four 25 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 141.73 265.31 72.69 235.3 92.66

table 3

Table 4 shows the parameters of each material layer of the AR film layer 3:

Table 4

As shown in Fig. 5, the optical filter of the present invention is set with reference to the parameters of each condition in Example 2. In the wavelength range of 800-1200nm, the IR film layer 2 of the present invention has a passband, two cut-off bands and two transition bands, that is, along the direction from 800nm-1200nm, the IR film layer 2 has a cut-off band, a transition band, a passband, a transition band and a cut-off band in sequence. The passband band refers to the band through which light can pass, the cut-off band refers to the band through which light cannot pass, and the transition band is located between the cut-off band and the passband band. As shown in the figure, the width of the passband band is less than 400nm, and the transmittance is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cut-off band is less than 0.1%.

As shown in FIG6 , the AR film layer 3 of the optical filter of the present invention is set with reference to the various condition parameters in Example 2. In the wavelength range of 350-1200 nm, the AR film layer 3 has a passband, a cutoff band and a transition band, that is, along the direction from 350 nm to 1200 nm, the AR film layer 3 has a cutoff band, a transition band and a passband in sequence. As shown in FIG6 , the light transmittance of the passband is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cutoff band is less than 0.1%.

The optical filter of the present invention is set according to the parameters of Example 2, which can also ensure that the half-maximum full width of the optical filter of the present invention is less than 120nm, the total thickness of the IR film layer 2 and the AR film layer is less than 9.8 microns, and when the incident angle changes from 0° to 30°, the center wavelength offset of the filter passband is less than 20nm.

Embodiment 3:

In this embodiment, along the direction away from the glass substrate 1, the structure of the IR film layer 2 of the filter is M, (LH)*n, L, wherein the optical thicknesses of the second refractive index material layer H, the third refractive index material layer M and the first refractive index material layer L are respectively one-quarter of the reference wavelength, the physical thickness of the second refractive index material layer H and the physical thickness of the first refractive index material layer L satisfy the relationship: 0.05≤D _L /D _H ≤20, and the physical thickness of the third refractive index material layer M and the physical thickness of the second refractive index material H satisfy the relationship: 0.02≤D _M /D _H ≤50. n＝11, and the total thickness of the IR film layer 2 is 4.64μm. Along the direction away from the glass substrate 1, the structure of the AR film layer 3 is (LH)*q, L, q＝12. The physical thickness of the second refractive index material layer H and the physical thickness of the first refractive index material layer L satisfy the relationship: 0.05≤D _L /D _H ≤20. The physical thickness of the third refractive index material layer M and the physical thickness of the second refractive index material layer H satisfy the relationship: 0.02≤D _M /D _H ≤50.

That is, in this embodiment, the IR film layer 2 includes 24 material layers, and the AR film layer 3 includes 25 material layers. In this embodiment, in the IR film layer 2, hydrogenated silicon is selected as the second refractive index material layer H, Nb ₂ O ₅ is selected as the third refractive index material layer M, and silicon dioxide is selected as the first refractive index material layer L. In the AR film layer 3, hydrogenated silicon is selected as the second refractive index material layer H, and silicon dioxide is selected as the first refractive index material layer L. Using the formula OT _i =OT(1+Acos(2×pi×f× i)sin(2×pi×f×i)), substitute into the equation The film parameters are as follows:

Table 5 shows the parameters of each material layer of the IR film layer 2:

table 5

Table 6 shows the parameters of each material layer of the AR film layer 3:

1 2 3 4 5 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 118.99 144.41 121.91 40.98 99.76 6 7 8 9 10 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 38.13 108.77 46.76 96.72 40 11 12 13 14 15 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) twenty one 105 114.2 162.36 134.9 16 17 18 19 20 Material Si:H SiO ₂ Si:H SiO ₂ Si:H Thickness(nm) 20 20 20 86.73 41.24 twenty one twenty two twenty three twenty four 25 Material SiO ₂ Si:H SiO ₂ Si:H SiO ₂ Thickness(nm) 117.94 60.05 45.65 53.89 139.6

Table 6

As shown in Fig. 7, the optical filter of the present invention is set with reference to the parameters of each condition in Example 3. In the wavelength range of 800-1200nm, the IR film layer 2 of the present invention has a passband, two cut-off bands and two transition bands, that is, along the direction from 800nm-1200nm, the IR film layer 2 has a cut-off band, a transition band, a passband, a transition band and a cut-off band in sequence. The passband band refers to the band through which light can pass, the cut-off band refers to the band through which light cannot pass, and the transition band is located between the cut-off band and the passband band. As shown in the figure, the width of the passband band is less than 400nm, the transmittance is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cut-off band is less than 0.1%.

As shown in FIG8 , the AR film layer 3 of the optical filter of the present invention is set with reference to the various condition parameters in Example 3. In the wavelength range of 350-1200 nm, the AR film layer 3 has a passband, a cutoff band and a transition band, that is, along the direction from 350 nm to 1200 nm, the AR film layer 3 has a cutoff band, a transition band and a passband in sequence. As shown in FIG8 , the light transmittance of the passband is greater than 90%, the transmittance of the transition band is 0.1%-90%, and the transmittance of the cutoff band is less than 0.1%.

The optical filter of the present invention is set according to the parameters of Example 3, which can also ensure that the half-maximum full width of the optical filter of the present invention is less than 120nm, the total thickness of the IR film layer 2 and the AR film layer is less than 9.8 microns, and when the incident angle changes from 0° to 30°, the center wavelength offset of the filter passband is less than 20nm.

The optical filter of the present invention is provided with the IR film layer 2 and the AR film layer 3 in the above manner, and while effectively ensuring the high transmittance of near-infrared light, the drift of the center wavelength of the filter passband with angle can be controlled to be less than 20nm. In addition, since the third refractive index material layer M is provided in the IR film layer 2 and the AR film layer 3, and arranged in the above arrangement form, the total film thickness of the optical filter of the present invention is effectively reduced, and the adhesion of the film layer can be improved.

The present invention also provides an infrared image sensing system including the optical filter of the present invention. FIG. 9 is a schematic diagram showing the structure of the infrared sensing system including the optical filter of the present invention. As shown in FIG. 9 , the infrared image sensing system of the present invention includes a light source unit 4 and a receiving unit 5. In the present embodiment, the light source unit 4 includes an IR emitting light source 41 and a first lens assembly 42. The receiving unit 5 includes a second lens assembly 51, the optical filter of the present invention and an infrared image sensor 53. In the present embodiment, the IR light source 41 can be a VCSEL (vertical cavity surface emitting laser), LD or LED, and the first lens assembly 42 includes a near-infrared light collimating lens and an optical diffraction element. The second lens assembly 51 can use an ordinary optical lens. The working process of the infrared image sensing system of the present invention is as follows:

The IR light source 41 is turned on, and after being collimated by the first lens assembly 42, the light is projected toward the face/hand 6. The second lens assembly 51 captures the image, and the infrared image sensor 53 generates a 3D image through algorithm calculation to perform face recognition or gesture recognition. Due to the presence of the filter 52 of the present invention, the near infrared light can be enhanced and the light of other wavelengths can be cut off during shooting, thereby improving the accuracy of the final face recognition and gesture recognition.

The above is only one solution of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. An optical filter comprising a glass substrate (1), and an IR film layer (2) and an AR film layer (3) plated on opposite surfaces of the glass substrate, wherein the IR film layer (2) is a near infrared band-pass film layer for passing near infrared light, the AR film layer (3) is a near infrared antireflection film layer for antireflection of near infrared light,

The IR film layer (2) comprises at least two first refractive index material layers, at least one second refractive index material layer and a single third refractive index material layer, the refractive index of the third refractive index material layer being greater than the refractive index of the first refractive index material layer, the refractive index of the second refractive index material layer being greater than the refractive index of the third refractive index material layer;

along the direction far away from the glass substrate (1), the structure of the IR film layer (2) is (LH) s, L, M, (LH) p and L in sequence, wherein M represents a third refractive index material layer, L represents a first refractive index material layer and H represents a second refractive index material layer, the (LH) s represents that the first refractive index material layer and the second refractive index material layer are alternately arranged for s times, s is an integer greater than or equal to 0, the (LH) p represents that the first refractive index material layer and the second refractive index material layer are alternately arranged for p times, and p is an integer greater than or equal to 1;

Along the direction far away from the glass substrate (1), the structure of the AR film layer (3) is sequentially (LH) q and L, wherein L represents a first refractive index material layer, H represents a second refractive index material layer, and (LH) q represents that the first refractive index material layer and the second refractive index material layer are alternately arranged for q times, and q is an integer greater than or equal to 1; or (b)

The structure of the AR film layer (3) is sequentially M, (LH) k and L, wherein M represents a third refractive index material layer, L represents a low refractive index material layer and H represents a second refractive index material layer, the (LH) k represents that the first refractive index material layer and the second refractive index material layer are alternately arranged for k times, and k is an integer greater than or equal to 1; or (b)

The structure of the AR film layer (3) is sequentially (LH) i, L, M, (LH) f and L, wherein M represents a third refractive index material layer, L represents a first refractive index material layer, H represents a second refractive index material layer, (LH) i represents that the first refractive index material layer and the second refractive index material layer are alternately arranged i times, i is an integer greater than or equal to 0, and (LH) f represents that the first refractive index material layer and the second refractive index material layer are alternately arranged f times, and f is an integer greater than or equal to 1.

2. The filter of claim 1, wherein the physical thickness of the second refractive index material layer and the physical thickness of the first refractive index material layer satisfy the relationship: d _L/D_H is more than or equal to 0.05 and less than or equal to 20; the physical thickness of the third refractive index material layer and the physical thickness of the second refractive index material layer satisfy the relation: d _M/D_H is more than or equal to 0.02 and less than or equal to 50.

3. The filter according to claim 1, wherein the IR film layer (2) second refractive index material layer is a silicon hydride layer, the refractive index in the wavelength range of 800-1200nm is more than 3, and the extinction coefficient is less than 0.002;

The second refractive index material layer has a refractive index greater than 3.6 at 850nm and a refractive index greater than 3.55 at 940 nm.

4. The filter of claim 3, wherein the silicon hydride layer is a sputter reaction plated material layer, the sputter temperature is in the range of 80-300 degrees celsius, the hydrogen flow is 10-50sccm, and the sputter rate is 0.1nm/s-1nm/s.

5. The filter of claim 1, wherein the refractive index of the third refractive index material layer is less than 4 and the refractive index of the first refractive index material layer is less than 3 in a wavelength range of 800-1200 nm.

6. The filter according to claim 1, characterized in that the IR film layer (2) has one passband, two cutoff bands and two transition bands in the wavelength range of 800-1200nm, the two transition bands being located on either side of the passband, the two cutoff bands being located outside the two transition bands, respectively;

The width of the passband wave band is smaller than 400nm, and the transmittance is larger than 90%;

the transmittance of the transition wave band is 0.1% -90%;

The transmittance of the cut-off wave band is less than 0.1%.

7. The optical filter according to claim 1, wherein the AR film layer (3) has one passband, one cutoff and one transition band in a wavelength range of 350-1200nm, the cutoff, transition and passband bands being sequentially arranged in a direction from 350nm to 1200 nm;

the transmissivity of the passband is greater than 90%;

the transmittance of the transition wave band is 0.1% -90%;

The transmittance of the cut-off wave band is less than 0.1%.

8. The filter according to claim 1, characterized in that the full width at half maximum value of the filter is less than 120nm, and the total thickness of the IR film layer (2) and the AR film layer (3) is less than 9.8 micrometers.

9. The filter of claim 1, wherein the center wavelength shift of the filter passband is less than 20nm when the angle of incidence is changed from 0 ° to 30 °.

10. An infrared image sensing system comprising the filter according to any of claims 1-9, characterized in that it comprises a light source unit (4) and a receiving unit (5),

The light source unit (4) includes an IR emitting light source (41) and a first lens assembly (42);

the receiving unit (5) comprises a second lens assembly (51), a filter (52) and an infrared image sensor (53).